Hydrotreating using self-promoted molybdenum and tungsten sulfide catalysts formed from bis(tetrathiometallate) precursors

ABSTRACT

Hydrocarbon feeds are upgraded by contacting same, at elevated temperature and in the presence of hydrogen, with a self-promoted catalyst formed by heating one or more carbon-containing, bis(tetrathiometallate) catalyst precursor salts selected from the group consisting of (NR 4 ) 2  [M(WS 4 ) 2  ], (NR 4 ) x  [M(MoS 4 ) 2  ] and mixtures thereof wherein R is one or more alkyl groups, aryl groups or mixture thereof, wherein promoter metal M is covalently bound in the anion and is Ni, Co or Fe and wherein x is 2 if M is Ni and x is 3 if M is Co or Fe composite in a non-oxidizing atmosphere in the presence of sulfur, hydrogen, and a hydrocarbon to form said supported catalyst.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hydroprocessing processes using self-promotedmolybdenum and tungsten sulfide hydrotreating catalysts. Moreparticularly, this invention relates to hydroprocessing processes suchas hydrotreating using self-promoted molybdenum and tungsten sulfidehydrotreating catalysts produced by heating one or more molybdenumand/or tungsten BIS(tetrathiometallate) catalyst precursor compoundscontaining the prometer metal as part of the precursor molecule in thepresence of sulfur at elevated temperature for a time sufficient to formsaid self-promoted catalyst.

2. Background of the Disclosure

The petroleum industry is increasingly turning to coal, tar sands, heavycrudes and resids as sources for future feedstocks. Feedstocks derivedfrom these heavy materials contain more sulfur and nitrogen thanfeedstocks derived from more conventional crude oils. Such feedstocksare commonly referred to as being dirty feeds. These feeds thereforerequire a considerable amount of upgrading in order to obtain usableproducts therefrom, such upgrading or refining generally beingaccomplished by hydrotreating processes which are well-known in thepetroleum industry.

These processes require the treating with hydrogen of varioushydrocarbon fractions, or whole heavy feeds, or feedstocks, in thepresence of hydrotreating catalysts to effect conversion of at least aportion of the feeds, or feedstocks to lower molecular weighthydrocarbons, or to effect the removal of unwanted components, orcompounds, or their conversion to innocuous or less undesirablecompounds. Hydrotreating may be applied to a variety of feedstocks,e.g., solvents, light, middle, or heavy distillate feeds and residualfeeds, or fuels. In hydrorefining relatively light feeds, the feeds aretreated with hydrogen, often to improve odor, color, stability,combustion characteristics, and the like. Unsaturated hydrocarbons arehydrogenated, and saturated. Sulfur and nitrogen are removed in suchtreatments. In the treatment of catalytic cracking feedstocks, thecracking quality of the feedstock is improved by the hydrotreating.Carbon yield is reduced, and gasoline yield is generally increased. Inthe hydrodesulfurization of heavier feedstocks, or residua, the sulfurcompounds are hydrogenated and cracked. Carbon-sulfur bonds are broken,and the sulfur for the most part is converted to hydrogen sulfide whichis removed as a gas from the process. Hydrodenitrogenation, to somedegree, also generally accompanies hydrodesulfurization reactions. Inthe hydrodenitrogenation of heavier feedstocks, or residua, the nitrogencompounds are hydrogenated and cracked. Carbon-nitrogen bonds arebroken, and the nitrogen is converted to ammonia and evolved from theprocess. Hydrodesulfurization, to some degree, also generallyaccompanies hydrodenitrogenation reactions. In the hydrodesulfurizationof relatively heavy feedstocks, emphasis is on the removal of sulfurfrom the feedstock. In the hydrodenitrogenation of relatively heavyfeedstocks, emphasis is on the removal of nitrogen from the feedstock.Although hydrodesulfurization and hydrodenitrogenation reactionsgenerally occur together, it is usually far more difficult to achieveeffective hydrodenitrogenation of feedstocks than hydrodesulfurizationof feedstocks.

Catalysts most commonly used for these hydrotreating reactions includematerials such as cobalt molybdate on alumina, nickel on alumina, cobaltmolybdate promoted with nickel, nickel tungstate, etc. Also, it iswell-known to those skilled in the art to use certain transition metalsulfides such as cobalt and molybdenum sulfides and mixtures thereof toupgrade oils containing sulfur and nitrogen compounds by catalyticallyremoving such compounds in the presence of hydrogen, which processes arecollectively known as hydrotreating or hydrorefining processes, it beingunderstood that hydrorefining also includes some hydrogenation ofaromatic and unsaturated aliphatic hydrocarbons. Thus, U.S. Pat. No.2,914,462 discloses the use of molybdenum sulfide for hydrodesulfurizinggas oil and U.S. Pat. No. 3,148,135 discloses the use of molybdenumsulfide for hydrorefining sulfur and nitrogen-containing hydrocarbonoils. U.S. Pat. No. 2,715,603 discloses the use of molybdenum sulfide asa catalyst for the hydrogenation of heavy oils, while U.S. Pat. No.3,074,783 discloses the use of molybdenum sulfides for producingsulfur-free hydrogen and carbon dioxide, wherein the molybdenum sulfideconverts carbonyl sulfide to hydrogen sulfide. Molybdenum and tungstensulfides have other uses as catalysts, including hydrogenation,methanation, water gas shift, etc., reactions.

In general, with molybdenum and other transition metal sulfide catalystsas well as with other types of catalysts, higher catalyst surface areasgenerally result in more active catalysts than similar catalysts withlower surface areas. Thus, those skilled in the art are constantlytrying to achieve catalysts that have higher surface areas. Morerecently, it has been disclosed in U.S. Pat. Nos. 4,243,553 and4,243,554 that molybdenum sulfide catalysts of relatively high surfacearea may be obtained by thermally decomposing selected thiomolybdatesalts at temperatures ranging from 300°-800° C. in the presence ofessentially inert, oxygen-free atmospheres. Suitable atmospheres aredisclosed as consisting of argon, a vacuum, nitrogen and hydrogen. InU.S. Pat. No. 4,243,554 an ammonium thiomolybdate salt is decomposed ata rate in excess of 15° C. per minute, whereas in U.S. Pat. No.4,243,553 a substituted ammonium thiomolybdate salt is thermallydecomposed at a very slow heating rate of from about 0.5° to 2° C./min.The processes disclosed in these patents are claimed to producemolybdenum disulfide catalysts having superior properties for water gasshift and methanation reactions and for catalyzed hydrogenation orhydrotreating reactions.

Catalysts comprising molybdenum sulfide in combination with other metalsulfides are also known. Thus, U.S. Pat. Nos. 2,891,003 discloses aniron-chromium combination for desulfurizing olefinic gasoline fractions;3,116,234 discloses Cr-Mo and also Mo with Fe and/or Cr and/or Ni forHDS; 3,265,615 discloses Cr-Mo for HDN and HDS; 3,245,903 disclosesFe-Mo and Fe-Co-Mo for lube oil refining; 3,459,656 discloses Ni-Co-Mofor HDS; 4,108,761 discloses Fe-Ni-Mo for HDN and 4,171,258 disclosesFe-Cr-Mo for HDS with steam.

SUMMARY OF THE INVENTION

The present invention relates to hydroprocessing processes comprisingcontacting a hydrocarbon feed, at elevated temperature and in thepresence of hydrogen; with a self-promoted hydroprocessing catalystobtained by heating one or more carbon-containing,bis(tetrathiometallate) catalyst precursor salts selected from the groupconsisting of (NR₄)₂ [M(WS₄)₂ ], (NR₄)_(x) [M(MoS₄)₂ ] and mixturesthereof, in a non-oxidizing atmosphere in the presence of sulfur andhydrogen at a temperature above about 150° C. for a time sufficient toform said catalyst, wherein (NR₄) is a carbon-containing, substitutedammonium cation and R is selected from the group consisting of (a) alkylgroups, aryl groups and mixture thereof and (b) mixtures of (a) withhydrogen, wherein promoter metal M is covalently bound in the anion andis Ni, Co or Fe and wherein x is 2 if M is Ni and x is 3 if M is Co orFe. In a preferred embodiment, substituted ammonium cation (NR₄) willcontain only alkyl groups. It is also preferred to form the catalyst inthe presence of a hydrocarbon. Self promoted means a promoted catalystof this invention formed from a precursor wherein the promoter metal iscovalently bound in the anion of the precursor salt as explained below.

Hydroprocessing processes is meant to include any process that iscarried out in the presence of hydrogen including, but not limited to,hydrocracking, hydrodenitrogenation, hydrodesulfurization, hydrogenationof aromatic and aliphatic unsaturated hydrocarbons, methanation, watergas shift, etc. These reactions include hydrotreating and hydrorefiningreactions, the difference generally being thought of as more of adifference in degree than in kind, with hydrotreating conditions beingmore severe than hydrorefining conditions.

DETAILED DESCRIPTION OF THE INVENTION

As hereinbefore stated, the catalyst precursor will be one or morecarbon containing bis(tetrathiomolybdate) or bis(tetrathiotungstate)compounds of the formula (NR₄)₂ [M(WS₄)₂ ] or (NR₄)_(x) [M(MoS₄)₂ ]wherein the promoter metal M is covalently bound in the anion and is Ni,Co or Fe and wherein x is 2 if M is Ni and x is 3 if M is Co or Fe. Ashereinbefore stated, R is a proton, an alkyl group, an aryl group ormixture thereof and preferably one or more alkyl groups. Thesebis(tetrathiometallate) anions have the structure ##STR1## wherein M' iseither Mo or W, and the promoter metal M is tetracoordinated with foursulfur atoms with each of the two tetrathiometallate groups providingtwo of the said four sulfur atoms. Thus, it will be appreciated that thecharge, 2- or 3-, on the bis(tetrathiometallate) anion will depend onthe charge or oxidation state of the promoter metal M. Thebis(tetrathiotungstate) and bis(tetrathiomolybdate) anions, [M(WS₄)₂ ]and [M(MoS₄)₂ ], will have a charge of 2- when the oxidation state ofthe promoter metal M is 2+. In contrast, they will have a charge of 3-if the oxidation state of promoter metal M is 1+. The precursors usefulin this invention may be prepared in both non-aqueous media and mixedaqueous/non-aqueous media. With the exception of compounds containingthe cobalt bis(tetrathiomolybdate) trianion, many compounds useful ascatalyst precursors in this invention and the methods used to preparethem may be found in an article by Callahan and Piliero titled"Complexes of d⁸ Metals with Tetrathiomolybdate and TetrathiotungstateIons. Synthesis, Spectroscopy and Electrochemistry," Inorg. Chem., 19,n. 9, 2619-2629 (1980) and in a review article by A. Muller et al inChem. Rev. 104, 975 (1971), the disclosures of which are incorporatedherein by reference.

Except for compounds containing the cobalt bis(tetrathiomolybdate)anion, compounds useful as catalyst precursors in this invention may beprepared, for example, in mixed aqueous/non-aqueous media such as anequal volume mixture of water and acetonitrile. Thus, one may formseparate solutions of a simple salt of the promoter metal (i.e., ahalide, sulfate, etc.) and an ammonium thiotungstate or thiomolybdate inthe mixed media. These solutions will then be mixed, preferably atrelatively low temperature and under anaerobic conditions. A salt of asuitable cation (i.e., NR₄ Cl) may be added to the promoter saltsolution or to the mixture of promoter metal salt and ammoniumthiometallate. The catalyst precursor (NR₄)_(x) [M(M'S₄)₂ ] precipitatesout of solution. The catalyst precursor compounds useful in thisinvention are stable in the presence of oxygen or air if they are keptdry, except for the (NR₄)₃ [Fe(MoS₄)₂ ] and (NR₄)₃ [Co(MoS₄)₂ ]precursor compounds which should be kept both dry and under anaerobicconditions.

Compounds of the formula (NR₄)₃ [Co(MoS₄)₂ ] containing the cobaltbis(tetrathiomolybdate) trianion [Co(MoS₄)₂ ]³⁻ of the structure setforth above wherein the cobalt is in the 1+ oxidation state have beenprepared in non-aqueous media using mono, di and trivalent cobaltcontaining compounds. If the cobalt in the cobalt containing startingmaterial is in the monovalent or 1+ oxidation state, a reducing agentneed not be present in the reaction media. However, a non-oxidizingenvironment is essential to form the trianion in significant amountsirrespective of whether the cobalt in the starting material is in themono, di or trivalent state. These compounds are preferably formed underanaerobic conditions. Illustrative, but non-limiting examples ofmonovalent cobalt starting materials useful for forming compoundscontaining the trianion [Co(MoS₄)₂ ]³⁻ include cyclopentadienyl cobaltdicarbonyl-(C₅ H₅)Co(CO)₂, hydridocobalt tetracarbonyl-HCo(CO)₄ andcyclopentadienyl cobalt cycloctatetraene-(C₅ H₅)Co(C₈ H₈).

When using a cobalt containing starting material wherein the cobalt isdi or trivalent, it is necessary for the cobalt to be converted to themonovalent form during the reaction in order for the product to beformed. The conversion into the monovalent cobalt form can be effectedby the presence of sufficient reducing agent in the reaction medium. Thereducing agent may be added to the reaction medium or it may be part ofthe cobalt containing compound used as one of the starting materials.

When a compound containing a divalent or trivalent cobalt atom is usedas a starting material, it is necessary for the cobalt to be convertedto the monovalent form during the formation of thebis(tetrathiomolybdate) trianion. The following reaction sequenceillustrates the formation of (NR₄)₃ [Co(MoS₄)₂ ] from CoCl₂ and (NR₄)₃(MoS₄) in the presence of a reducing agent such as an organic thiolate,SR⁻, wherein R is hydrogen, an alkyl group, an aryl group or mixturethereof and preferably an alkyl group. ##STR2## Thus when the simplesalt CoCl₂, where the cobalt is divalent, is used as a startingmaterial, it is first reacted with a thiolate reagent, SR⁻, to form theanion Co(SR)₄ ²⁻. The thiolate reagent SR⁻ is generated by reacting thethiol RSH with a base. Although any base may be used, such as NaOH, itis preferred to use a nitrogen containing organic base such as pyridine,or a primary, secondary or tertiary amine. In equation (1) above, thebase is a trialkylamine. Although only a stoichiometric amount ofreducing agent SR⁻ is needed to effect the reduction from Co²⁺ to Co¹⁺,it is preferred to use an excess of reducing agent. The solutioncontaining the anion Co(SR)₄ ²⁻ is then added to the (NR₄)₂ MoS₄,partially dissolved in CH₃ CN (eq. 2). After a period of 30 to 60minutes, the reaction is complete. Since the product (NR₄)₃ [Co(MoS₄)₂ ]is the least soluble in the reaction mixture, it can be readilyprecipitated out of the solution by adding diethylether to the reactionmixture.

When the cobalt starting material already contains the reducing agentbonded to it, for example Co(S₂ CNR'₂)₃, it can be directly reacted with(NH₄)₂ MoS₄. Equation 3 illustrates this reaction wherein R' is alkyl,aryl or mixture thereof and preferably alkyl. ##STR3## In this example,the cobalt starting material has cobalt in the trivalent state. Threeequivalents of the reducing agent, N,N-dialkyl dithiocarbamate, S₂ CNR'₂⁻, are coordinated with the Co³⁺. In this reaction,N,N-dimethylformamide is the preferred solvent. Further, this reactionrequires heating at 70° C. and at least 10 hours for the reaction togive significant yield of the product. The reducing agent gets oxidizedto tetraalkylthiuramdisulfide (S₂ CNR'₂)₂ as the Co³⁺ gets converted toCo¹⁺. Examples of other reducing agents that are capable of coordinatingwith cobalt include alkyl or aryl xanthates (S₂ COR'⁻),o,o-dialkyldithiophosphates (S₂ P(OR')₂ ⁻), dialkyldithiophosphinates(S₂ PR'₂ ⁻) or thiolates (SR'⁻).

It should be understood that other reducing agents such as dithionitesalts, borohydride salts, hydrazines, etc., can be used as the reductantin this synthesis route when other cobalt 2+ or 3+ compounds orcomplexes are used as the cobalt starting material. These includecomplex ions in which N, O, S or P are coordinated to the cobalt atom.Illustrative, but non-limiting examples of other suitable cobalt 2+ and3+ compounds and complexes include salts of Co(amine)₆ ²⁺,3+,Co(acetylacetonate)₃, salts of [Co(NH₃)₅ Cl]²⁺, etc.

The cobalt bis(tetrathiomolybdate) trianion compounds prepared as abovewere analyzed using a variety of analytical techniques. Thus, elementalanalysis was done by using combustion analysis for carbon, nitrogen,hydrogen and sulfur while atomic absorption spectroscopy was used toanalyze for the metals. Infrared and electronic absorption spectroscopywere also employed as well as magnetic susceptibility and x-ray powderdiffraction spectroscopy. In the infra-red region, characteristic bandsof the trianion of this invention, Co(MoS₄)₂ ³⁻, were observed at 481cm⁻¹, 466 cm⁻¹ and at 445 cm⁻¹. In the ultraviolet-visible-nearinfra-red region, a N,N-dimethylformamide solution of the (NR₄)⁺ salt(wherein R was C₂ H₅) displayed peaks at 825 nm, (400), 645 nm (6,600),545 nm (5,300), 453 nm (sh) and at 394 nm (19,500). The parentheticalnumbers are molecular extinction coefficients in units of liter mole⁻¹cm⁻¹. The complex (NR₄)₃ [CO(MoS₄)₂ ] wherein R=C₂ H₅ displayed amagnetic moment of 3.3 BM as determined by the Evans NMR method.

Inasmuch as compounds containing the cobalt bis(tetrathiomolybdate)trianion are sensitive to oxygen, they must be maintained undernon-oxidizing and preferably anaerobic conditions.

The catalysts of this invention may be prepared by heating one or morecatalyst precursor salts, in the presence of sulfur and hydrogen and ata temperature of from about 150°-600° C., for a time sufficient to formthe catalyst. Preferably, the temperature will range from about200°-500° C. and more preferably from about 300°-400° C. In a preferredembodiment the catalyst will be formed in the presence of a hydrocarbon,in addition to sulfur and hydrogen.

The sulfur required for the formation of the catalyst from the precursorshould be present in an amount at least sufficient to achieve thedesired stoichiometry of the resulting catalyst. It should be noted thatit is possible to make catalysts of this invention using only the sulfurpresent in the precursor. However, it is preferred that additionalsulfur be present during formation of the catalyst. This additionalsulfur may be present as elemental sulfur or a sulfur-bearing compoundother than the precursor. Preferably, sulfur will be present in thereaction zone in an amount in excess of the stoichiometrically requiredamount. The hydrogen required to form the catalyst may be present in thereaction as gaseous hydrogen, a hydrogen-bearing gas such as H₂ S, oneor more hydrogen donor hydrocarbons such as tetralin, or combinationthereof. In one preferred embodiment the catalyst will be formed fromthe precursor in-situ in a sulfur bearing hydrocarbon feed.

In a preferred embodiment, the catalysts of this invention will beformed ex-situ or in situ in the presence of any hydrocarbon that isconvenient, including a heavy hydrocarbon oil having at least 10 weightpercent of material boiling above about 1050° F. at atmosphericpressure, such as various residua, whole and topped crude oils, etc.Thus, the catalysts of this invention may be formed in situ in asulfur-bearing feed merely by contacting one or more suitable precursorcompounds useful in forming the catalysts of this invention with thefeed and hydrogen at a temperature above about 150° C. and preferablyabove about 200° C. After the catalyst has been formed in-situ, thecatalyst will then act to remove sulfur from said feed if hydrogen ispresent therein. As previously stated, the hydrogen may be present inthe feed as gaseous hydrogen, a hydrogen-bearing gas such as H₂ S, oneor more hydrogen donor hydrocarbons such as tetralin, or combinationthereof.

As discussed under Background of the Disclosure, molybdenum and tungstensulfide catalysts have many uses, including hydrotreating. Hydrotreatingconditions vary considerably depending on the nature of the hydrocarbonbeing hydrogenated, the nature of the impurities or contaminants to bereacted or removed, and, inter alia, the extent of conversion desired,if any. In general however, the following are typical conditions forhydrotreating a naphtha boiling within a range of from about 25° C. toabout 210° C., a diesel fuel boiling within a range of from about 170°C. to 350° C., a heavy gas oil boiling within a range of from about 325°C. to about 475° C., a lube oil feed boiling within a range of fromabout 290°-550° C., or residuum containing from about 10 percent toabout 50 percent of material boiling above about 575° C.

Finally, the catalysts of this invention are also useful for removingnitrogen from nitrogen containing feedstocks. They are particularlyuseful for selectively removing nitrogen from a nitrogen and sulfurcontaining feed, such as a lube oil feed.

    __________________________________________________________________________                             Space                                                                              Hydrogen                                                          Pressure                                                                             Velocity                                                                           Gas Rate                                        Feed        Temp., °C.                                                                   psig   V/V/Hr                                                                             SCF/B                                           __________________________________________________________________________    Naptha                                                                              Typical                                                                             100-370                                                                             150-800                                                                               0.5-10                                                                            100-2000                                        Diesel                                                                              Typical                                                                             200-400                                                                             250-1500                                                                             0.5-4                                                                              500-6000                                        Fuel                                                                          Heavy Typical                                                                             260-430                                                                             250-2500                                                                             0.3-2                                                                              1000-6000                                       Gas Oil                                                                       Lube Oil                                                                            Typical                                                                             200-450                                                                             100-3000                                                                             0.2-5                                                                                100-10,000                                    Residuum                                                                            Typical                                                                             340-450                                                                             1000-5000                                                                            0.1-1                                                                               2000-10,000                                    __________________________________________________________________________

The invention will be more readily understood by reference to thefollowing examples.

EXAMPLE 1

1.3 ml of HSC₆ H₅ and 1.75 ml of N(C₂ H₅)₃ were added to a suspension of0.669 g of CoCl₂ in CH₃ CN. The resulting green solution was added to asuspension of 4.9 g of [N(C₂ H₅)₄ ]₂ MoS₄ in CH₃ CN. The mixture wasstirred and a dark green solution gradually resulted. Within 30 minutes,the reaction was completed and the solution was filtered. The product,[N(C₂ H₅)₄ ]₃ [Co(MoS₄)₂ ] was precipitated by adding diethylether tothe filtrate. The precipitated product was filtered, washed withdiethylether, methanol and diethylether again. One gram of this catalystprecursor was pressed under 15,000-20,000 psi and then sieved through10/20 mesh or 20/40 mesh sieves. One gram of this meshed catalystprecursor was mixed with 10 g of 1/16-in. spheroid porcelain beads andplaced in the catalyst basket of a Carberry-type autoclave reactor. Theremainder of the basket was filled with more beads. The reactor wasdesigned to allow a constant flow of hydrogen through the feed and topermit liquid sampling during operation.

After the catalyst precursor and beads were charged to the reactor, thereactor system was flushed with helium for about 30 minutes after whichhydrogen flow through the reactor was initiated at a rate of 100 cc/min.After the hydrogen began flowing through the reactor, the reactor wascharged with 100 cc of a feed comprising a DBT/Decalin mixture which wasprepared by dissolving 4.4 g of dibenzothiophene (DBT) in 100 cc of hotDecalin. The solution thus contained about 5 wt.% DBT or 0.8 wt.% S. Thehot feed solution was filtered and 1 cc of decane was added.

After the feed was charged to the reactor, the hydrogen pressure wasincreased to about 450 psig and the temperature in the reactor raisedfrom room temperature to about 350° C. over a period of about 1/2 hourduring which time the catalyst was formed in-situ in the reactor. Thehydrogen flow rate through the reactor was maintained at about 100 ccper minute. When the desired temperature and pressure were reached, a GCsample of liquid was taken and additional samples taken at one hourintervals thereafter. The liquid samples from the reactor were analyzedusing a Gow Mac Series 550 Gas Chromatograph.

As the reaction progressed, samples of liquid were withdrawn once anhour and analyzed by GC chromatography in order to determine theactivity of the catalyst towards hydrodesulfurization as well as itsselectivity for hydrogenation. The hydrodesulfurization activity wasdetermined according to the following model reaction: ##STR4## Thehydrodesulfurization zero order rate constant, r, for the catalyst wasfound to be 370×10¹⁶ molecules of DBT desulfurized per gram of MoS₂ inthe catalyst per second as shown in the Table. This rate issignificantly higher than that of a catalyst formed from (NH₄)₂ MoS₄ andtested in a similar manner which had a rate constant, r, of 45×10¹⁶.

EXAMPLE 2

The Co complex, [N(C₂ H₅)₄ ]₂ [Co(WS₄)₂ ], was prepared in a mannersimilar to that described by Callahan and Piliero for the preparation ofNi(WS₄)₂ ²⁻. Thus CoCl₂.6H₂ O (1.54 g) in a mixture of 40 ml water and40 ml CH₃ CN was acidified with about 4 ml glacial acetic acid. Thissolution was deaerated with argon gas for about 5-10 mins. after whichit was added, dropwise, to a similarly deaerated, stirred solution of4.34 g (NH₄)₂ WS₄ in 160 ml of a 1:1 mixture of CH₃ CN/H₂ O. A blacksolution formed. After addition was completed, 6 g. [N(C₂ H₅)₄ ]Br in 60of a 1:1 mixture of CH₃ CN/H₂ O (deaerated with argon) was added to theblack solution. A brown crystalline precipitate of [N(C₂ H₅)₄ ]₂[Co(WS₄)₂ ] formed. After stirring for 30 minutes at 0° C., the product,[N(C₂ H₅)₄ ]₂ [Co(WS₄)₂ ], was filtered under argon, washed with water,then methanol followed by diethyl ether and air dried. The yield was 5.3g (89%).

A catalyst was formed in-situ and its activity was measured using thesame procedure described in Example 1. The resulting in-situ formedcatalyst had a rate constant of 167×10¹⁶ molecules of DBTconverted/sec.-gm of WS₂ as shown in the Table. This example shows thatcompounds containing the bis(tetrathiotungstate) dianion are usefulprecursors for forming the catalysts of this invention.

EXAMPLE 3

A nickel self-promoted catalyst precursor, [N(C₃ H₇)₄ ]₂ [Ni(MoS₄)₂ ],was prepared using known literature methods in an analogous fashion toExample 2. Thus, (NH₄)₂ MoS₄ (15.3 g) was partially dissolved in 180 mlof a 1:1 (by volume) mixture of water and CH₃ CN. The solvent mixturewas previously deaerated with argon gas for a period of about 10minutes. To the above stirred solution was added slowly a deaeratedsolution mixture of NiCL₂.6H₂ O (6.75 g) and [N(C₃ H₇)₄ ]Br in 180 ml ofa 1:1 (by volume) mixture of water and Ch₃ CN. The reaction mixture wascooled to 0° C. in an ice bath. The red catalyst precursor product wasfiltered in air, washed with methanol and ether, then dried under vacuumfor several hours. The yield was practically quantitative. The precursorwas sieved, etc. and a catalyst formed in-situ using the procedure inExample 1.

The activity of the resulting catalyst was found to be 239×10¹⁶molecules of DBT converted/sec.-gm of MoS₂ as shown in the Table.

EXAMPLE 4

A [N(C₂ H₅)₄ ]₂ [Ni(MoS₄)₂ ] catalyst precursor was prepared using thesame procedure in Example 3, except that [N(C₂ H₅)₄ ]Br was used insteadof [N(C₃ H₇)₄ ]Br. A catalyst was formed in-situ and tested using theprocedure set forth in Example 1. The activity is listed in the Tableand was 134×10¹⁶.

EXAMPLE 5

Example 2 was repeated, but NiCl₂.6H₂ O was used instead of CoCl₂.6H₂ Owhich formed the catalyst precursor [N(C₂ H₅)₄ ]₂ [Ni(WS₄)₂ ]. Thecatalyst formed in-situ from this precursor had an activity of 169×10¹⁶and is set forth in the table.

EXAMPLE 6

Example 5 was repeated using [N(C₃ H₇)₄ ]Br instead of [N(C₂ H₅)₄ ]BR toform the catalyst precursor [N(C₃ H₇)₄ ]₂ [Ni(WS₄)₂ ]. The activity ofthe resulting catalyst is listed in the Table and was 164×10¹⁶.

EXAMPLE 7

A [N(C₂ H₅)₄ ]₂ [Fe(WS₄)₂ ] catalyst precursor was prepared using themethod described by Miller et al [A. Muller and S. Sarker, Angew. Chem.Int'l., Ed. Engl., 16 (19), 705 (1977)]. Thus, 144 g of FeSO₄.7H₂ O and0136 g of N₂ H₄.HCl were dissolved in 50 ml of degassed water to whichwas added a degassed solution of 4.59 g of [N(C₂ H₅)₄ ]₂ WS₄ in 50 ml ofwater. The precursor precipitated out of solution as a dark greenprecipitate which was filtered under argon, washed with water, ethanoland ether and then dried. This yielded 2.6 g of catalyst precursor.

A catalyst was formed in-situ from the precursor and tested using theprocedure in Example 1. The activity of the catalyst was 55×10¹⁶ and islisted in the Table.

EXAMPLE 8

In this Example, a [N(C₃ H₇)₄ ]₃ [Fe(MoS₄)₂ ] catalyst precursor wasformed under nitrogen by first dissolving 21.0 g of (NH₄)₂ MoS₄ and 44.8g of [N(C₃ H₇)₄ ]Br in a mixture of 500 ml of H₂ O and 200 ml of CH₃ CN.To this solution was added, with stirring, suspension of 15 g ofFe(NH₄)₂ SO₄ in a mixture of 150 ml of H₂ O and 100 ml of CH₃ CN. Atfirst a brown precipitate formed. However, by the time that all of thesuspension was added, a black tar and a purplish red suspension hadformed. On standing overnight the black tar had solidified into a darkmass which was broken up in the suspension and stirred for a day toobtain a dark purplish precipitate. This precipitate was the catalystprecursor and was filtered, washed twice with water, washed with ethanoland dried under vacuum.

The procedure set forth in Example 1 was used both to form the catalystfrom the precursor in-situ in the feed and evaluate the resultingcatalyst. The resulting catalyst had an activity of 60×10¹⁶ which is setforth in the Table.

EXAMPLE 9

This experiment used the same catalyst precursor feed and procedure,etc. as Example 1 to evaluate the catalyst. However, this experiment wasdifferent than Examples 1-8 in that the catalyst was not formed from theprecursor in-situ in the feed solution, but was pre-formed in an H₂ S/Hmixture prior to contacting the hot, sulfur bearing hydrocarbon feed.Thus, a catalyst was formed by contacting a precursor, [N(C₂ H₅)₄ ]₃[Co(MoS₄)₂ ] with a flowing mixture of 15% H₂ S in H₂ for one hour at325° C. The activity of the catalyst was found to be 255×10¹⁶.

Referring to the Table, it can be seen that when a catalyst was formedfrom the same precursor in-situ in the sulfur bearing feed, the HDSactivity of the resulting catalyst was about twice that of a catalystformed in an H₂ S/H₂ mixture.

    __________________________________________________________________________    HDS ACTIVITY OF THIOHETEROANION DERIVED CATALYSTS.sup.1                                             Activity × 10.sup.-16 /gm                                                          Activity × 10.sup.-16 /gm              Example #                                                                           Precursor   % MS.sub.2                                                                        Precursor.sup.3                                                                          MS.sub.2.sup.3                               __________________________________________________________________________    1     [N(C.sub.2 H.sub.5).sub.4 ].sub.3 Co(MoS.sub.4).sub.2                                     35.7                                                                              167        468                                          2     [N(C.sub.2 H.sub.5).sub.4 ].sub.2 Co(WS.sub.4).sub.2                                      52.6                                                                              88         167                                          3     [N(C.sub.3 H.sub.7).sub.4 ].sub.2 Ni(MoS.sub.4).sub.2                                     36.4                                                                              87         239                                          4     [N(C.sub.2 H.sub.5).sub.4 ].sub.2 Ni(MoS.sub.4).sub.2                                     41.8                                                                              56         134                                          5     [N(C.sub.2 H.sub.5).sub.4 ].sub.2 Ni(WS.sub.4).sub.2                                      52.6                                                                              89         169                                          6     [N(C.sub.3 H.sub.7).sub.4 ].sub.2 Ni(WS.sub.4).sub.2                                      46.9                                                                              77         164                                          7     [N(C.sub.2 H.sub.5).sub.4 ].sub.2 Fe(WS.sub.4).sub.2                                      52.7                                                                              29          55                                          8     [N(C.sub.3 H.sub.7).sub.4 ].sub.3 Fe(MoS.sub.4).sub.2                                     30.1                                                                              18          60                                          9     [ N(C.sub.2 H.sub.5).sub.4 ].sub.3 Co(MoS.sub.4).sub.2                                    63  161        255                                          __________________________________________________________________________     .sup.1 All catalysts were formed insitu except for Example 9.                 .sup.2 Amount of MS.sub.2 (M is Mo or W) contained in the precursor in        percent.                                                                      .sup.3 The activity is in molecules of DBT converted per sec per gm.          precursor or MS.sub.2.                                                   

EXAMPLE 10

In this experiment a sample of the [N(C₃ H₇)₄ ]₂ [Ni(MoS₄)₂ ] catalystprecursor prepared in Example 3 was ground and pelletized to a 20/40mesh size (Tyler) using a four percent aqueous solution of polyvinylalcohol as a binder. The pelletized catalyst precursor was placed into astainless steel reactor at 100° C. at atmospheric pressure where it waspurged for one hour under nitrogen. Ten percent of hydrogen sulfide inhydrogen was introduced into the reactor at a space velocity of 0.75SCF/hr for each 10 cc of catalyst precursor in the reactor. Thetemperature in the reactor was then raised to 325° C. and kept at thistemperature for three hours to form the catalyst after which thetemperature in the reactor was lowered to 100° C., the H₂ S/H₂ gas flowwas stopped and the reactor was purged with nitrogen until roomtemperature was reached.

About 20 cc of the catalyst was loaded into a fixed-bed reactor made outof 3/8 inch 316 stainless steel pipe which was equipped with acalibrated feed burette pump, gas-liquid separator and liquid productcollector. The conditions in the reactor were as set forth below:

Temperature--325° C.

Pressure--3.15 MPa

Hydrogen rate--3000 SCF/bbl

LHSV--3.0

The liquid product was analyzed for total sulfur by X-ray fluorescenceand for nitrogen by combustion analysis. The feedstock used was a lightcatalytic cycle oil (LCCO) that was about 20 wt.% paraffinic havingproperties set forth in Table 2.

                  TABLE 2                                                         ______________________________________                                        LCCO Feed                                                                     ______________________________________                                        Gravity (°API)                                                                         18.6                                                          Sulfur, wt. %    1.5                                                          Nitrogen, ppm   370                                                           ______________________________________                                        GC distillation                                                               Wt. %           Temp., °C.                                             ______________________________________                                         5              231                                                           10              251                                                           50              293                                                           70              321                                                           90              352                                                           95              364                                                           ______________________________________                                    

This catalyst was found to have an HDS rate constant (K_(HDS)) of 8.9and an HDN (K_(HDN)) rate constant of 4.4. The rate constants for thehydrodesulfurization and hydrodenitrogenation reactions were calculatedas follows: ##EQU1## wherein S_(f) and S_(p) are the weight percent ofsulfur in the feed and product, respectively and N_(f) and N_(p) are theweight percent of nitrogen in the feed and product, respectively. Itshould be noted that the catalyst of this invention had a much higherselectivity for nitrogen removal than commercial cobalt molybdate onalumina and nickel molybdate on alumina catalysts.

By selectivity for nitrogen removal is meant the ratio of the HDN rateconstant times 100. Thus, the selectivity for nitrogen removal of thecatalyst of this invention was 49.4 whereas for the commercial cobaltmolybdate on alumina it was 5.14 and for the nickel molybdate on aluminait was 12.48.

What is claimed is:
 1. A hydrocracking process comprising contacting ahydrocarbon feed at elevated temperature and in the presence of hydrogenwith a catalyst obtained by heating one or more carbon-containing,bis(tetrathiometallate) catalyst precursors selected from the groupconsisting of (NR₄)₂ [M(WS₄)₂ ], (NR₄)_(x) [M(MoS₄)₂ ] and mixturesthereof, in a non-oxidizing atmosphere in the presence of sulfur andhydrogen at a temperature above about 150° C. for a time sufficient toform said catalyst, wherein (NR₄) is a carbon-containing, substitutedammonium cation, wherein promoter metal M is covalently bound in theanion and is Ni, Co or Fe and wherein x is 2 if M is Ni and x is 3 if Mis Co or Fe, said contacting occurring for a time sufficient tohydrocrack at least a portion of said feed.
 2. The process of claim 1wherein said feed is contacted with said catalyst at a temperature of atleast about 100° C.
 3. The process of claim 2 wherein said catalyst isformed in the presence of excess sulfur.
 4. The process of claim 3wherein said catalyst is formed in the presence of one or morehydrocarbons.
 5. The process of either of claims 1, 3 or 4 wherein R isselected from the group consisting of (a) alkyl groups, aryl groups andmixtures thereof and (b) mixtures of (a) with hydrogen.
 6. The processof claim 5 wherein said excess sulfur is present in the form of sulfurbearing compounds.
 7. The process of claim 6 wherein the substitutedammonium cation contains only alkyl groups.
 8. The process of claim 7wherein said hydrogen containing, non-oxidizing atmosphere used to formsaid catalyst comprises a mixture of H₂ and H₂ S.
 9. The process ofclaim 5 wherein the substituted ammonium cation contains only alkylgroups.
 10. The process of either of claims 1, 2, or 4 wherein said feedis a lube oil feed.
 11. The process of claim 5 wherein said feed is alube oil feed.
 12. The processof claim 8 wherein said feed is a lube oilfeed.
 13. A process for hydrorefining a hydrocarbon feed which comprisescontacting said feed at an elevated temperature of at least about 100°C. and in the presence of hydrogen with a catalyst obtained by heatingone or more carbon-containing, bis(tetrathiometallate) catalystprecursor salts selected from the group consisting of (NR₄)₂ [M(WS₄)₂ ],(NR₄)_(x) [M(MoS₄)₂ ] and mixtures thereof, in a non-oxidizingatmosphere in the presence of sulfur and hydrogen at a temperature aboveabout 150° C. for a time sufficient to form said catalyst, wherein (NR₄)is a carbon-containing, substituted ammonium cation and R is selectedfrom the group consisting of (a) alkyl groups, aryl groups and mixturethereof and (b) mixtures of (a) with hydrogen, wherein promoter metal Mis covalently bound in the anion and is Ni, Co or Fe and wherein x is 2if M is Ni and x is 3 if M is Co or Fe, said contacting occurring for atime sufficient to hydrorefine at least a portion of said feed.
 14. Theprocess of claim 13 wherein said catalyst is formed in the presence ofexcess sulfur.
 15. The process of claim 14 wherein said catalyst isformed in the presence of hydrogen.
 16. The process of claim 15 whereinsaid excess sulfur is in the form of one or more sulfur bearingcompounds.
 17. The process of claim 16 wherein said substituted ammoniumcation contains only alkyl groups.
 18. The process of claim 17 whereinsaid non-oxidizing atmosphere comprises a mixture of H₂ and H₂ S. 19.The process of either of claims 13, 15, or 16 wherein said feed is alube oil feed.
 20. The process of claim 19 wherein said feed containssulfur at least a portion of which is removed by said hydrorefiningprocess.
 21. A process for removing nitrogen from a nitrogen-containinghydrocarbon feed which comprises contacting said feed at elevatedtemperature and in the presence of hydrogen with a catalyst obtained byheating one or more carbon-containing, bis(tetrathiometallate) catalystprecursor salts selected from the group consisting of (NR₄)₂ [M(WS₄)₂ ],(NR₄)_(x) [M(MoS₄)₂ ] and mixtures thereof, in a non-oxidizingatmosphere in the presence of sulfur and hydrogen at a temperature aboveabout 150° C. for a time sufficient to form said catalyst, wherein (NR₄)is a carbon-containing, substituted ammonium cation and R is selectedfrom the group consisting of (a) alkyl groups, aryl groups and mixturethereof and (b) mixtures of (a) with hydrogen, wherein promoter metal Mis covalently bound in the anion and is Ni, Co or Fe and wherein x is 2if M is Ni and x is 3 if M is Co or Fe, said contacting occurring for atime sufficient to remove at least a portion of nitrogen from said feedto produce a feed of reduced nitrogen content.
 22. The process of claim21 wherein said catalyst is formed in the presence of excess sulfur. 23.The process of claim 22 wherein said catalyst is formed in the presenceof one or more hydrocarbons.
 24. The process of claim 23 wherein saidfeed is contacted with said catalyst at a temperature of at least about150° C.
 25. The process of claim 24 wherein said excess sulfur used forforming said catalyst comprises one or more sulfur bearing compounds.26. The process of claim 25 wherein said substituted ammonium cation ofsaid catalyst precursor contains only alkyl groups.
 27. The process ofclaim 26 wherein said non-oxidizing atmosphere used in forming saidcatalyst comprises a mixture of hydrogen and H₂ S.
 28. The process ofeither of claims 21, 24, 26 or 27 wherein said hydrocarbon feed is alube oil feedstock.